Irish monk, teacher, astronomer, and poet who flourished about 820. He is mentioned in 811 as an Irish priest and scholar at the monastery of St-Denis near Paris. In that year he wrote a letter to Charlemagne explaining the eclipse of the sun which was supposed to have taken place in 810. In one of Alcuin's letters (M. G., Epp., IV, 437) he is alluded to as a bishop. In 823 he is mentioned in a "capitulary" of Lothair, and in 825 in an imperial decree by which he was appointed "master" of the school at Pavia. This is the last mention of Dungal in the public records of the empire. In 827 or 828 he appeared against Claudius, Bishop of Turin, in a work defending the veneration of images. From the fact that he bequeathed his books to the library of St. Columbanus at Bobbio it is inferred that he spent his last days in the Irish monastery on the Trebbia. The date of his death is unknown. His books, many of them at least, were transferred by Cardinal Federigo Borromeo to the Ambrosian Library in Milan, where they now are.

Some historians doubt whether the Dungal of St-Denis and the adversary of Claudius are one person. The prevalent opinion, however, is that they are one and the same. In his letter to Charlemagne Dungal brings to bear on the question of eclipses a knowledge of astronomy far beyond the current ideas of the time. His "Reply" to Claudius is enriched with many citations from the Greek and Latin Fathers and from the liturgical hymns of the Church. The poems ascribed in most manuscripts to Exul Hibernicus are believed by Dümmler, editor of the "Poetæ Ævi Carolini", to have been written by Dungal, who like many of his fellow-exiles from Ireland styles himself peregrinus, exul, pauper et peregrinus. Only three of them bear the name Dungal. They are interesting from many points of view, especially from that of the historian who searches the records of Charlemagne's reign for the all too scanty references to the personal feelings and the attitude of mind of the Irish scholars who flocked to the Continent of Europe in the ninth century. Yet they do not enable us to determine when and where Dungal was born, though from the fact that among his books which he presented to the Library of Bobbio is the "Antiphonary of Bangor", it is inferred that he spent the ears of his student life in Ireland at the famous Bangor school. Mabillon published a ninth-century poem from which it appears that Dungal enjoyed among his contemporaries a reputation for more than ordinary learning.